中文摘要：

食线虫真菌是植物寄生线虫的重要天敌，它们所产生的胞外水解酶（蛋白酶、几丁质酶和胶原蛋白酶等）能够降解线虫体壁和卵壳中的蛋白质及几丁质等结构成分并在侵染过程中发挥着重要的作用。本文中，我们发现刀孢轮枝菌Lecanicillium psalliotae对南方根结线虫Meloidogyne incognita卵具有较强的侵染能力。为了进一步研究刀孢轮枝菌胞外几丁质酶的性质，我们通过简并引物设计和DNAwalking方法从刀孢轮枝菌的基因组中成功地克隆得到一个内切几丁质酶基因Lpchil，该几丁质酶编码基因含有3个内含子，编码423个氨基酸。同源性和系统发育分析表明，不同生防真菌来源的几丁质酶具有较高的同源性并根据分子量的大小形成三个不同的进化分枝。

英文摘要：

Nematophagous fungi, one of the natural enemies of nematodes, have been employed in biological control. Extracellular enzymes secreted fi＇om nematophagous fungi, including protease, chitinase and collagenase serve as virulence factors of infection. In this study, we found Lecanicillium psalliotae can penetrate the eggs of the root-knot nematode Meloidogyne incognita and influence development of the eggs. A chitinase gene Lpchil was isolated from L. psalliotae using degenerate primers and DNA-walking technique. Comparison of the chitinase amino acid sequences from different pathogenic fungi revealed that the enzymes were highly similar. The phylogenetic analysis demonstrated that the chitinases derived from different fungi were clustered into three main clades corresponding to different molecular weight.